The solubility of Pell equation ax3-by2=±1(a,b∈Z+，ab is a non-square positive integer)is a very meaningful question.In this paper,by applying related knowleged of Legendre sign and nature of congruence,it works out six conclusions to judge that the sets of Pell equations such as px2-(pn±2)y2=±1(p≡-1,±3（mod 8）,and p is a prime number)have not positive integer solutions.These conclusions play an important role in the research onrestricted Pell equation x2-Dy2=±1(D is a non-square positive integer)